溫度感應性有機無機混成凝膠製備與性質之研究

STUDY ON PREPARATION AND PROPERTIES OF THERMOSENSITIVE ORGANIC-INORGANIC HYBRID GELS

黃偉仁(Wei-Jen Huang)

指導教授 ： 李文福

大同大學/工程學院/化學工程學系所/碩士(2010年)

摘要

Poly(N-isopropylacrylamide), (PNIPAAm), 水膠在32℃水溶液中具有熱可逆性膨潤收縮行為，此溫度稱之為臨界膠體轉移溫度。將無機成分導入以製備有機無機混成材料將影響膠體之性質。本研究中，藉由導入矽烷單體和NIPAAm以乳化聚合法與溶膠凝膠反應來製備有機無機混成膠體，並且探討矽烷耦合劑、IPN結構、TEOS含量、silica含量以及silica的改質對於混成膠體膨潤度、膨潤動力以及機械性質之影響。結果顯示膨潤與機械性質主要受到由於無機成分與矽烷單體所造成之各種不同膠體結構所影響。
首先以乳化聚合法與溶膠凝膠反應製備三種不同結構之有機無機混成凝膠：N-IPN膠體[N-isopropylacrylamide (NIPAAm)、 N, N’-methylenebisacrylamide (NMBA) 與 tetraethoxysilane (TEOS)]；NT-IPN膠體[NIPAAm、 耦合劑3-(trimethoxysilyl) propyl methacrylate (TMSPMA)與TEOS]；NT-semi-IPN膠體[NIPAAm、TMSPMA與TEOS]。此部份探討膠體結構以及耦合劑對於膨潤行為、機械強度以及膠體型態之影響。結果顯示膠體性質會受到結構如IPN或semi-IPN、耦合劑TMSPMA存在與否的影響。由於在semi-IPN的結構中PNIPAAm並未受到NMBA交聯網目的束縛，因此NT-semi-IPN膠體具有較高的膨潤度以及較快的擴散速率。然而，IPN膠體如N-IPN與NT-IPN具有較佳的機械性質以及較低的膨潤度，但是溫度敏感性相對較差，這是由於系統中所添加的耦合劑TMSPMA使得有機與無機部分具有較緊密的結合所致。IPN結構的膠體從SEM型態的觀察中發現有局部矽氧烷(siloxane)的堆積以及一些較緊密的相。
進一步探討TEOS含量對於膨潤行為、機械性質以及膠體型態的影響。結果顯示膠體性質會受到結構如IPN或semi-IPN、耦合劑TMSPMA存在與否以及TEOS含量的影響。結構因素的結果如同前述。增加TEOS含量將會降低溫度敏感性與膨潤度。當TEOS含量增加，會產生相分離並造成較鬆散的膠體結構，因此機械強度與交聯密度也會下降。
此外，以奈米二氧化矽微粒以及改質奈米二氧化矽微粒取代TEOS導入系統中製備混成膠體，並探討無機奈米二氧化矽微粒對於此系列膠體之膨潤行為與機械性質的影響。結果顯示隨著奈米二氧化矽微粒添加量增加或是導入矽烷耦合劑皆會導致膠體膨潤度降低，但是會使得機械強度增強。以溶膠凝膠反應將胺基矽烷接載在奈米二氧化矽表面以進行改質，並導入膠體系統中探討二氧化矽微粒的改質對於交体性質之影響。結果顯示含有改質二氧化矽的膠體具有較高的膨潤度以及機械強度。同時包含矽烷耦合劑與二氧化矽微粒的膠體具有較高的交聯密度，這是由於二氧化矽微粒的交聯網目透過矽烷耦合劑和有機網目有較緊密之結合。

關鍵字

水膠 ； 溫度感應性 ； 有機無機混成 ； 矽氧烷 ； 矽烷耦合劑 ； 互穿高分子網目

並列摘要

Poly(N-isopropylacrylamide), PNIPAAm, hydrogels are well known to show thermally reversible swelling-deswelling behavior around 32℃ in aqueous solutions with respect to a critical gel transition temperature (CGTT). Introducing inorganic moiety to prepare organic-inorganic hybrid gels can affect some properties of hydrogels. In this research, organic-inorganic hybrid gels were prepared by introducing silane monomers to copolymerize or crosslink with PNIPAAm by emulsion polymerization and sol-gel reaction, and the effects of silane coupling agent, IPN structure, TEOS content, silica content, and modification of silica on swelling ratios, swelling kinetics, and mechanical properties of hybrid gels were investigated. The results showed that the swelling and mechanical properties would be mainly affected by various situation of gel structure caused by introduction of inorganic moiety and the silane coupling agent.
A series of organic-inorganic hybrid thermosensitive gels with three different structures were prepared from N-isopropylacrylamide (NIPAAm), and N, N’-methylenebisacrylamide (NMBA) and tetraethoxysilane (TEOS) [N-IPN]; NIPAAm, 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) as coupling agent and TEOS [NT-IPN]; and NIPAAm, TMSPMA and TEOS [NT-semi-IPN] by emulsion polymerization and sol-gel reaction. The effect of different gel structures and coupling agent on the swelling behavior, mechanical properties, and morphologies of the present gels was investigated. Results showed that the properties of the gels would be affected by the gel networks such as IPN or semi-IPN and with or without existence of TMSPMA as the bridge chain between networks. The NT-semi-IPN gel had higher swelling ratio and faster diffusion rate because poly (NIPAAm) moiety in the semi-IPN gels was not restricted by NMBA network. However, the IPN gels such as N-IPN and NT-IPN had good mechanical properties and lower swelling ratio, but had a poor thermosensitivity due to the addition of coupling agent, TMSPMA, into the gel system that resulted in denser link between organic and inorganic components. The morphology showed that IPN gels had partial aggregation (siloxane domain) and showed some denser phases.
Further discussion of above-mentioned series, the effect of TEOS content on the swelling behavior, mechanical properties, and morphologies of the present gels was investigated. Results showed that the properties of the gels would be affected by the gel networks such as IPN or semi-IPN, existence of TMSPMA as the bridge chain between networks, and content of TEOS. The results of effect on gel structure were similar as mentioned before. The swelling ratios and thermosensitivity of the hybrid gels decreased with an increase of TEOS content. As the content of TEOS increased, the phase separation occurred that resulted in loosen gel structure and consequently showed a weaker modulus and lower crosslinking density.
Moreover, nanosilica and modified nanosilica were introduced into this system to replace the TEOS and the effect of inorganic nano-silica on swelling behaviors and mechanical properties were investigated by adding different amount of nano-silica and modified nano-silica. Results showed that the swelling ratios of the hybrid gels decrease with increasing nano-silica content. Existence of silane coupling agent would also reduce the swelling ratios of the hybrid gels. Adding coupling agent or nano-silica would improve the gel strength. Modification of nano-silica by grafting amino-silane via sol-gel process was carried out and the effect of addition of modified silica on gel properties was also investigated. Results showed that the hybrid gels containing modified silica would have higher swelling ratios and moduli than those containing unmodified silica. Gels containing both silane coupling agent and silica would have higher crosslinking density because the silica would be better crosslinked with coupling agent.

並列關鍵字

hydrogel ； thermosensitive ； organic-inorganic hybrid ； siloxane ； silane coupling agent ； interpenetrating networks

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